some useful function process date:
CALL FUNCTION 'DATE_GET_MONTH_LASTDAY' "获取本月最后一天
EXPORTING
i_date = l_tempdata_s
IMPORTING
e_date = l_tempdata_e.
CALL FUNCTION 'BKK_GET_MONTH_LASTDAY' "获取本月最后一天
EXPORTING
i_date = riqi1
IMPORTING
e_date = riqi2.
CALL FUNCTION 'MONTH_PLUS_DETERMINE' "获取N月前的日期
EXPORTING
months = -N
olddate = sy-datum
IMPORTING
NEWDATE = newdate.
CALL FUNCTION 'MONTHS_BETWEEN_TWO_DATES' "计算两个日期间的月份差
EXPORTING
i_datum_bis = p_l_startday
i_datum_von = P_l_endday
* I_KZ_INCL_BIS = ' '
IMPORTING
E_MONATE = p_l_months
.